''Labidesthes sicculus'', also known as the Brook silverside is a

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

n species of

Neotropical silverside The Neotropical silversides are a family, Atherinopsidae, of fishes in the order Atheriniformes. About 112 species in 13 genera are distributed throughout the tropical and temperate waters of the New World, including both marine and freshwater h ...

. The brook silverside lives in slow moving

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

s and

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

s from the

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...

to the

Mississippi Basin The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it fl ...

and

Gulf Coastal Plains The Gulf Coastal Plain extends around the Gulf of Mexico in the Southern United States and eastern Mexico. This coastal plain reaches from the Florida Panhandle, southwest Georgia, the southern two-thirds of Alabama, over most of Mississippi, wes ...

. The brook silverside survives best in clear water with aquatic vegetation. ''L. sicculus'' feeds on a diet of

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

s, insect

larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

, and winged

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

s. The spawning season of the brook silverside occurs during the spring and early summer. The survival of freshwater fishes such as the brook silverside is increasingly threatened. In order to ensure survival of the brook silverside, turbidity of natural habitats should be monitored.

Geographic distribution

The distribution of brook silverside populations range from the Great Lakes southward through the Mississippi Basin and Gulf Coastal Plains (including 27 U.S. states and parts of Canada). It is native to the majority of this distribution, but has also been stocked outside of its natural range as forage food for sport fishes.Jonna, R. (2004)
Actinopterygii.
NatureServe. The brook silverside occupies freshwater lakes, ponds, quiet pools and small rivers. The environment ranges from cool to warm water Marsden, J.E., Langdon, R.W. & Good, S.P. (2000): First occurrence of the brook silverside (''Labidesthes sicculus'') in Lake Champlain, Vermont. ''Northeastern Naturalist, 7 (3): 248-254.'' with variability in levels of gradient and vegetation. Consistently, however, the brook silverside prefers clear water with low substrate concentrations. The brook silverside is vulnerable to turbid waters.Powles, P.M. & Sandeman, I.M. (2008): Growth, summer cohort output, and observations on the reproduction of brook silverside, ''Labidesthes sicculus'' (Cope) in the Kawartha Lakes, Ontario. ''Environmental Biology of Fishes, 82 (4): 421-431.'' In

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

, brook silverside populations were shown to have decreased shortly after the construction of the Tennessee-Tombigbee Waterway. Populations likely declined because of introduced competition.Strongin, K., Taylor, C.M., Roberts, M.E., Neill, W.H. & Gelwick, F. (2011): Food Habits and Dietary Overlap of Two Silversides in the Tennessee-Tombigbee Waterway: The Invasive ''Menidia audens'' Versus the Native ''Labidesthes sicculus''. ''The American Midland Naturalist, 166 (1): 224-233.''

Ecology

The brook silverside is on the lower end of the food chain, and is preyed on by many larger fish. The diet of the brook silverside consists mostly of

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

. They are highly specialized feeders with

cladocera The Diplostraca or Cladocera, commonly known as water fleas, are a superorder of small crustaceans that feed on microscopic chunks of organic matter (excluding some predatory forms). Over 1000 species have been recognised so far, with many more ...

ns comprising 80% of their diet, (40%) small flying insects, and (20%) midge larvae. Their diet varies with life stages and seasons. At a younger age, the brook silverside preys mostly on smaller fish. Their diet shifts to immature insects later. During winter, the brook silverside eats mostly planktonic crustaceans. Because of both intentional and unintentional species introduction, the brook silverside must compete for food sources. Specifically, the brook silverside has been forced to compete with the non-native '' Menidia audens'', which was introduced by waterway construction. This forced competition of resources has led to a decrease in brook silverside populations.

Life history

The brook silverside breeds in the summer from late May to mid-August. Their life span is only one year. During the first year, they have rapid growth, growing up to one millimeter per day. Brook silversides quickly reach a maximum size of approximately eight centimeters. They reach sexual maturity by the first summer in order to reproduce. Some studies report that brook silversides reproduce by internal fertilization, although this has not been entirely confirmed. When the eggs are produced, they have an attached filament, which allows for the eggs to be deposited on logs, plants and rocks. Temperature does not affect the sex of fish. After the eggs hatch, they immediately swim away from the shore into deeper water, but still stay just under the surface. They congregate in large schools. The brook silverside migrates throughout its life cycle. No human-induced changes are reported as affecting the life history.Hubbs, C.L. (1921): An Ecological Study of the Life-History of the Fresh-Water Atherine Fish ''Labidesthes sicculus''. ''Ecology, 2 (4): 262-276.'' Human-induced changes are reported as more strongly affecting populations rather than behaviors.

Current management

Human intervention through species introduction, habitat alteration, pollution, and construction are causing the decline of the brook silverside and other freshwater fishes. Freshwater fishes account for the majority of extinctions in ray-finned fishes. To stabilize and increase populations, no more dams or waterways should be built. Additionally, pollution must be stopped. Agricultural runoff creates turbid waters, which the brook silverside cannot thrive in. Stream sampling occurs through organizations such as USFWS and TVA (locally). This allows for populations to be monitored and stream chemistry to be controlled. Over-fishing and hybridization aren't causing brook silverside populations to decline. Invasive species and habitat destruction have the greatest impact on population decline. Areas are being reserved for the preservation of endemic fish, but more must still be done.

References

{{Taxonbar, from=Q143344 Brook silverside Fish of the Great Lakes Fish described in 1865 Freshwater fish of North America